/*
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at https://mozilla.org/MPL/2.0/.
 */

package ca.gosyer.jui.domain.updates.interactor

import ca.gosyer.jui.domain.build.BuildKonfig
import ca.gosyer.jui.domain.server.Http
import ca.gosyer.jui.domain.updates.model.GithubRelease
import ca.gosyer.jui.domain.updates.service.UpdatePreferences
import io.ktor.client.call.body
import io.ktor.client.request.get
import kotlinx.coroutines.Dispatchers
import kotlinx.coroutines.IO
import kotlinx.coroutines.flow.catch
import kotlinx.coroutines.flow.flow
import kotlinx.coroutines.flow.flowOn
import kotlinx.coroutines.flow.singleOrNull
import me.tatarka.inject.annotations.Inject
import org.lighthousegames.logging.logging

class UpdateChecker
    @Inject
    constructor(
        private val updatePreferences: UpdatePreferences,
        private val client: Http,
    ) {
        suspend fun await(
            manualFetch: Boolean,
            onError: suspend (Throwable) -> Unit = {},
        ) = asFlow(manualFetch)
            .catch {
                onError(it)
                log.warn(it) { "Failed to check for updates" }
            }
            .singleOrNull()

        fun asFlow(manualFetch: Boolean) =
            flow {
                if (!manualFetch && !updatePreferences.enabled().get()) return@flow
                val latestRelease = client.get(
                    "https://api.github.com/repos/$GITHUB_REPO/releases/latest",
                ).body<GithubRelease>()

                if (isNewVersion(latestRelease.version)) {
                    emit(Update.UpdateFound(latestRelease))
                } else {
                    emit(Update.NoUpdatesFound)
                }
            }.flowOn(Dispatchers.IO)

        sealed class Update {
            data class UpdateFound(
                val release: GithubRelease,
            ) : Update()

            data object NoUpdatesFound : Update()
        }

        // Thanks to Tachiyomi for inspiration
        private fun isNewVersion(versionTag: String): Boolean {
            // Removes prefixes like "r" or "v"
            val newVersion = versionTag.replace("[^\\d.]".toRegex(), "")

            return if (BuildKonfig.IS_PREVIEW) {
                // Preview builds: based on releases in "Suwayomi/Suwayomi-JUI-preview" repo
                // tagged as something like "r123"
                newVersion.toInt() > BuildKonfig.PREVIEW_BUILD
            } else {
                // Release builds: based on releases in "Suwayomi/Suwayomi-JUI" repo
                // tagged as something like "v1.1.2"
                newVersion != BuildKonfig.VERSION
            }
        }

        companion object {
            private val GITHUB_REPO = if (BuildKonfig.IS_PREVIEW) {
                "Suwayomi/Suwayomi-JUI-preview"
            } else {
                "Suwayomi/Suwayomi-JUI"
            }

            private val RELEASE_TAG: String by lazy {
                if (BuildKonfig.IS_PREVIEW) {
                    "r${BuildKonfig.PREVIEW_BUILD}"
                } else {
                    "v${BuildKonfig.VERSION}"
                }
            }

            val RELEASE_URL = "https://github.com/$GITHUB_REPO/releases/tag/$RELEASE_TAG"

            private val log = logging()
        }
    }
